1. Technical Field
The present invention relates to resin compositions for semiconductor encapsulation and semiconductor devices.
2. Related Art
Recent trends towards higher density and higher integration in electronic components and semiconductor devices, such as integrated circuits (ICs), large scale integrated circuits (LSIs), and very-large-scale integrated circuits (VLSIs) stimulate conversion of packaging from insertion mounting to surface mounting. Such trends require lead frames with an increased number of pins and leads with narrower intervals. Surface mount quad flat packages (QFPs), which are compact and lightweight, are used for a variety of semiconductor devices. These semiconductor devices are generally encapsulated with epoxy resin compositions, which have high compatibility among high productivity rates, low material costs, and high reliability.
Since these epoxy resin compositions for semiconductor encapsulation must be nonflammable, brominated epoxy resins, such as tetrabromobisphenol A epoxy resins and brominated phenol novolak epoxy resins, and antimony oxide, as flame retardants, are compounded to main components.
In recent years, however, use of halogenated compounds, which involve the risk of generation of dioxin analogs, and highly toxic antimony compounds has been regulated for the purpose of environmental protection. In resin compositions for semiconductor encapsulation, technology on fire retardancy that does not use halogenated compounds, such as brominated epoxy resins, and antimony oxide has been studied. When semiconductor devices are preserved at high temperatures of 150 to 200° C. for long hours, bromine atoms and antimony compounds in the flame retardants cause an increase in resistance of the semiconductor devices and disconnection of gold wires. From this viewpoint, epoxy resin compositions for semiconductor encapsulation not containing bromine flame retardants or antimony compounds are required. Metal oxide flame retardants, such as aluminum hydroxide and magnesium hydroxide, have been used instead of bromine flame retardants or antimony compounds. Unfortunately, these metal oxide flame retardants lead to an increase in viscosity of melt resins and a decrease in soldering resistance of the composition.
Japanese Unexamined Patent Application Publication Nos. 2004-203911 and 2004-155841 disclose epoxy resin compositions for semiconductor encapsulation containing epoxy resins having biphenyl aralkyl skeletons. Although these epoxy resin compositions do not contain flame retardants, they exhibit high flame retardancy. Furthermore, these epoxy resin compositions have advantages of low moisture absorption, low modulus when being heated, high adhesiveness, resulting in production of highly reliable semiconductor devices. A disadvantage of these resins, however, is high production costs.
An object of the present invention is to provide an epoxy resin composition for semiconductor encapsulation which does not contain a brominated flame retardant or an antimony compound, exhibit high flame resistance, and high soldering resistance after humidified, and has an advantage of low material and production costs.
Another object of the present invention is to provide a semiconductor device encapsulated by the cured resin composition.